Abstract
Antiferromagnetic pyrite compound MnTe_2 is a newly discovered high-performance thermoelectric material. However, its electric and thermal transport performance remained unexplored so far. In this work, the first-principle calculations based on the density functional theory were applied to predict the electric and thermal transport performance of MnTe_2. The band structures showed that Te atoms dominate the band energies near the fermi level. The calculated electric transport performance of MnTe_2 from BoltzTraP2 package showed that n-type MnTe_2 possesses a higher power factor than that of p-type in the carrier concentration range from 10~(19) to 10~(21) cm~(-3). The peak power factor with electronic relaxation time of n-type MnTe_2 at 800 K is 3.05 x 10~(15) μW K~2 cm~(-1) s~(-1) at a lower carrier concentration of 0.78 × 10~(21) cm~(-3) while p-type is 2.18 × 10~(15) μW K~(-2) cm~(-1) s~(-1) at a higher carrier concentration of 1.35 × 10~(21) cm~(-3) It suggests that high-performance n-type doped MnTe_2 is easier to be obtained experimentally. Due to the low average phonon velocity of 2064 m-s~(-1), MnTe_2 has a low lattice thermal conductivity of 0.72 W m~(-1) K~(-1) at 800 K. The calculated charged point defect formation energy of several possible n-type doping elements showed that Y or La substituting Mn atom and Cl or Br substituting Te atom are the most possible n-type doping point defects. Combined with the optimal carrier concentration of 0.78 x 10~(21) cm~(-3)at 800 K, stoichiometric A_(0.07)Mn_(0.93)Te_2 (A = Y, La) and MnTe-1.93B0.07 (B = Cl, Br) are expected to possess high thermoelectric properties reaching the theoretical peak power factor with electronic relaxation time of 3.05× 10~(15) μW K~(-2) cm~(-1) s~(-1) and the lattice thermal conductivity of 0.72 W m~(-1) K~(-1).
NSTL
Elsevier